# Replace Elements with Greatest Element on Right Side in C++

Suppose we have an array A. We have to replace every element by the greatest element on the right side of this element. And replace the last one by -1. So if A = [5, 17, 40, 6, 3, 8, 2], then it will be [40,40,8,8,8,2,-1]

To solve this, we will follow these steps −

• We will read the array element from right to left.
• take e := -1
• for i := n – 1 to 0
• temp := e
• e := max between e and array[i]
• array[i] := temp
• return array

## Example

Let us see the following implementation to get better understanding −

Live Demo

#include <bits/stdc++.h>
using namespace std;
void print_vector(vector<int> v){
cout << "[";
for(int i = 0; i<v.size(); i++){
cout << v[i] << ", ";
}
cout << "]"<<endl;
}
class Solution {
public:
vector<int> replaceElements(vector<int>& arr) {
int rep = -1;
int n = arr.size();
for(int i = n - 1; i >= 0; i--){
int temp = rep;
rep = max(rep, arr[i]);
arr[i] = temp;
}
return arr;
}
};
main(){
Solution ob;
vector<int> c = {5,17,40,6,3,8,2};
print_vector(ob.replaceElements(c)) ;
}

## Input

[5,17,40,6,3,8,2]

## Output

[40,40,8,8,8,2,-1]